Apparatus and method for changing pattern plates on shell casting molding machine

ABSTRACT

A pattern plate carrier releasably mounts a pattern plate. The pattern plate carrier is rotatable to an inverted position, and a pattern plate changing device is provided for removing a pattern plate from the inverted carrier and replacing the removed pattern plate with a pre-heated substituting pattern plate.

BACKGROUND OF THE INVENTION

The invention relates to an apparatus for changing pattern plates in theproduction of Croning shell molds, wherein the pattern plate being inuse has a working temperature from about 250° C. to 330° C. Furthermore,the invention relates to a method of changing pattern plates during theproduction of Croning shell molds, in particular with the use of thetool changing apparatus in accordance with the invention.

Croning shell molds are casting molds for sand casting, which are usedin the so-called Croning shell molding process. Croning shell molds areproduced by means of rotatable, heated pattern plates, over which amolding box or a pouring vessel is placed. On its side carrying thepattern contour, the pattern plate is supplied or coated with apourable, thermosetting molding material, for example, molding sand. ACroning shell mold, also known as mold shell is formed, if possible,under the action of a vacuum applied to the rear side of the patternplate, and by the caking as well as curing of the molding material onthe heated surface of the pattern plate. The thickness of the shell isdependent on the curing time or temperature. Once the desired thicknessof the shell formed by the molding material is reached, the entirearrangement is tilted by 180°. In this process, the molding materialthat has not cured drops from the shell under the action of gravity, orfalls again into the pouring vessel. Since such a mold shell alone isunable to resist high casting pressures, it is often backfilled andcompacted on its rear side with a conventional molding material. Thisoccurs normally, in that the pattern plate, together with the mold boxor the pouring vessel is tilted again by 180° and filled thereafter witha molding sand as is commonly used in the foundry practice, such asgreen sand, which may again be compacted under the action of a pressuredifference between the pattern plate and the sand surface. Subsequently,the pouring vessel together with the thus-produced casting mold israised upward from the pattern plate. This upward movement may beassisted by an overpressure which acts upon the shell mold surface fromthe side of the pattern plate.

An apparatus for making Croning shell molds of the above-described typeis known, for example, from DE-OS 34 44 342 and corresponding EuropeanPatent 0184090. This type of apparatus includes pattern plates--insingle station or multistation arrangements--that are generally mountedby mechanical means, such as, for example, screws or the like, to apattern plate carrier. In this arrangement, a change of pattern platesis always connected with a prolonged shutdown of the entire arrangement.During such a change, the operating personnel are exposed toconsiderable thermal and physical stress as a result of the patternplates that are heated in the machine to temperatures from 250° C. to330° C.

A further and quite considerable disadvantage of the known arrangementmay be seen in that during a tool change, the substituting patternplates are supplied to the pattern plate carrier substantially at roomtemperature, so that prior to a renewed production of shell molds, it isnecessary to heat the substituting pattern plate in the machine. This istime-intensive and requires a prolonged shutdown of the machine in theform of a preparation time.

It is therefore the object of the present invention to provide a toolchanging device for changing pattern plates during the production ofCroning shell molds, which facilitates a faster and yet simpler exchangeof pattern plates in the machine without prolonged shutdown times. It isa further object to provide a corresponding method of changing patternplates during the production of Croning shell molds.

SUMMARY OF THE INVENTION

The above and other objects and advantages of the present invention areachieved by the provision of an apparatus and method for exchangingpattern plates used in the production of shell casting molds and whereinthe removed pattern plate is replaced with a substituting pattern platewhich is pre-heated to the working temperature.

In accordance with the invention, it has been found that atime-intensive heating of a substituting pattern plate caused quitesubstantial shutdown times of the machine. These shutdown times can beavoided in that the substituting pattern plate is already preheated tothe working temperature that is required in the machine. This can berealized in a surprisingly simple manner by providing a specialpreheating device, which prepares the substituting pattern plate.Therefore, after a change of pattern plates, a heating phase of thesubstituting pattern plate is no longer necessary. Instead, theproduction of Croning shell molds may start immediately after installingthe new pattern plate. Time-intensive and, consequently, cost-intensiveshutdown times are thus largely avoided, at least with respect to theconventional heating of the substituting pattern plate. Furthermore, thereplaced pattern plate may also be allowed to gradually cool on or inthe preheating device, after deactivating same, so that even to this endno further handling problems are incurred.

With respect to construction, it will be highly advantageous, when thepreheating device is associated with a pattern plate exchange carriage,which travels in the region of the carrier mounting the pattern plate.This pattern plate exchange carriage may also be used for receiving thepattern plate that is to be replaced, so that it is possible toaccommodate thereon both the substituting pattern plate and the patternplate being replaced. To this end, it would also be possible to providethe pattern plate exchange carriage with at least two supports forreceiving the pattern plates and two preheating devices respectivelyassociated with the supports. These preheating devices may be activatedindependently of each other and employ electric heaters or, for example,even gas burners.

The pattern plate in use is mounted on a carrier which is rotatable,preferably about a horizontal axis, and connected, via a couplingdevice, to a pouring vessel that is likewise rotatable, preferably abouta horizontal axis. When pivoting the pouring vessel upward, the patternplate carrier may be disconnected from the pouring vessel. Afterdisconnecting the pattern plate carrier, same may be again rotated,together with the pattern plate, to a downward directed transferposition. To this end, the pattern plate is rotated downward, preferablyby 180°.

More specifically, the pouring vessel may be arranged for pivoting abouta horizontal axis formed on the side facing away from the pattern platecarrier, by means of a pivoting device that is operative preferably viaa rocking lever. The pattern plate carrier itself may be arranged forrotation about a horizontal axis, preferably formed in the center, withthe axis of rotation of the pouring vessel on the one hand and that ofthe pattern plate carrier on the other extending parallel to oneanother. Essential in any event is that the pattern plate carrier be byall means supported for rotation or pivotal movement, it being possibleto make total use of this anyhow present rotatability for the toolchange.

The coupling device that operates between the pattern plate carrier andthe pouring vessel may comprise a coupling jaw, preferably associatedwith the pouring vessel, and a coupling shaft, preferably associatedwith the pattern plate carrier, as well as coupling rolls, if need be.When raising the pouring vessel, the coupling claw associated theretodisengages from the coupling shaft associated with the pattern platecarrier, so that the pattern plate carrier can be rotated or pivotedabout its preferably central axis.

With respect to a fully automatic tool change, it will be further ofadvantage, when the pattern plate exchange carriage can be brought ormoved below the preferably downward rotated pattern plate carrier. Thismovement could occur by hand, an electric motor, or via a hydraulic orpneumatic cylinder. In any event, it is essential that the pattern plateexchange carriage be movable directly below the downward rotated patternplate carrier, so that it is necessary to remove only the pattern platesupported on the pattern plate carrier and to raise a substitutingpattern plate toward the pattern plate carrier.

For raising or lowering the pattern plates being exchanged, it would bepossible to provide in a further advantageous manner, below the patternplate carrier, a lifting mechanism with a receiving device, which can bemoved, respectively for removing or lowering, or for raising orinstalling the pattern plate, toward same or toward the pattern platecarrier. Once the pattern plate exchange carriage is positioned, thelifting mechanism or its receiving device can extend through the patternplate exchange carriage, so that the pattern plate can be removed fromthe pattern plate carrier, or raised from the pattern plate exchangecarriage, and that it can again be deposited thereon.

In the case of removing a pattern plate from the pattern plate carrier,it is necessary that the pattern plate be first disengaged from thecarrier. To this end, the receiving device of the lifting mechanism maybe provided with preferably two disengagement cylinders for opening andclosing a pattern plate clamping connection that is arranged on thepattern plate carrier. After disengagement, the receiving device takesover the released pattern plate and lowers same to the pattern plateexchange carriage. When raising a substituting pattern plate, thedisengagement cylinders will again act upon the pattern plate clampingconnection, this time for securing or clamping the substituting patternplate to the carrier.

With respect to a very fast and successive removal of the old patternplate in use and an exchange for a new pattern plate, it will beparticularly advantageous, when the pattern plate exchange carriage hasat least two supports for receiving the pattern plates, and when it canbe positioned with the respective receiving support or pattern platebelow the preferably downward rotated pattern plate carrier and abovethe lifting mechanism or its receiving device. In such an event, it isonly necessary to remove or lower the pattern plate being replaced, andto raise the substituting pattern plate from the exchange carriage andto push same toward, and secure it to the empty pattern plate carrier.

The method of changing pattern plates in accordance with the presentinvention includes the steps of releasing and removing a pattern platefrom the pattern plate carrier, and then releasably mounting on thepattern plate carrier a substituting pattern plate which has beenpre-heated to its working temperature. Therefore, within the scope ofthe method in accordance with the invention, it is likewise notnecessary to heat the pattern plate in the machine. Instead, a newpattern plate for making Croning shell molds can be used immediatelyafter an exchange, without heating the pattern plate in the machine. Itis only necessary to maintain the process temperature.

In a further advantageous manner, the method of the present invention ischaracterized by the following detailed steps:

First, the pattern plate carrier is disengaged from the pouring vesselby raising same. Thereafter, the pattern plate carrier can be rotated,preferably about a central axis of rotation, and it can be pivoted orrotated, together with the pattern plate, preferably by 180°, to adownward directed transfer position. Subsequently, a pattern plateexchange carriage is moved or brought below the now downward rotatedpattern plate carrier.

By means of a lifting mechanism, a receiving device is now moved towardthe downward rotated pattern plate, the pattern plate being disengagedby means of the receiving device or disengagement cylinders associatedthereto. After disengaging the pattern plate, same is lowered onto afree receiving support of the pattern plate exchange carriage.Thereafter, the pattern plate exchange carriage is positioned below thepattern plate carrier for positioning the preheated substituting patternplate. Same is then raised by the receiving device and pushed againstthe until now empty pattern plate carrier. In like manner as for itsrelease, but only in the reversed sense, the substituting pattern plateis now again secured to the pattern plate carrier by means of thedisengagement cylinders. Thereafter, the lifting mechanism or thereceiving device retract, so that the pattern plate exchange carriage isable to move again out of the working or pivoting range of the patternplate carrier.

Finally, the pattern plate carrier is rotated back and reconnected tothe pouring vessel by lowering same. The production of new Croning shellmolds may proceed after a completed tool change.

BRIEF DESCRIPTION OF THE DRAWINGS

Some of the objects and advantages of the present invention having beenstated, others will appear as the description proceeds, when consideredin conjunction with the accompanying drawings, in which:

FIGS. 1-9 are schematic side views of an embodiment of a tool changingapparatus in accordance with the invention, the figures illustrating asequence of individual steps of the method during a tool change; and

FIG. 1A is a side elevation view of the pattern plate carrier of theapparatus of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Shown in FIGS. 1-9 are the individual operating steps, which a toolchange apparatus of the present invention performs when changing patternplates during the production of Croning shell molds not shown in thefigures. A pattern plate 1 that is in use has a working temperature fromabout 250° C. to 330° C.

In accordance with the invention, a preheating device 3 is provided,which is used to prepare a substituting pattern plate 2 and to maintainsame at the working temperature.

As best seen in the figures, the preheating device 3 is associated witha pattern plate exchange carriage 4. Same serves on the one hand toprepare the substituting pattern plate 2 and, on the other hand, toreceive the pattern plate 1 that is replaced. To this end, the patternplate exchange carriage 4 is provided with two supports 5 for receivingtwo pattern plates 1, 2, each support 5 mounting a preheating device 3.In the illustrated embodiment, the preheating device 3 is a gas burningdevice. The preheating devices 3 of both supports 5 can be activatedindependently of each other.

The tool changing device of the present invention is a device which isto be viewed in combination with a pattern plate carrier 6 and a pouringvessel 7. The pattern plate 1 in use is supported by pattern platecarrier 6, which is rotatable about a horizontal axis and connected, viaa coupling device 8, with pouring vessel 7 that is rotatable likewiseabout a horizontal axis. By pivoting the pouring vessel 7 upward, samereleases the pattern plate carrier 6, so that after its disengagement,the pattern plate carrier 6 can be rotated, together with the patternplate 1, by 180° to a downward directed transfer position.

More specifically, the pouring vessel 7 is rotatable by means of apivoting device 10 that is operative via a rocking lever 9, namely aboutan axis of rotation provided on the side of pouring vessel 7, whichfaces away from pattern plate carrier 6. In contrast therewith, thepattern plate carrier 6 is rotatable about a horizontal axis formed inits center, or it is freely rotatable after disengaging from pouringvessel 7. Essential is in any event that the axes of rotation of pouringvessel 7 and of pattern plate carrier 6 extend parallel to one another,namely perpendicular to the plane of the figure.

Furthermore, as clearly shown in the figures, the coupling device 8comprises a coupling claw 11 associated with the pouring vessel 7 and acoupling shaft 12 associated to the pattern plate carrier 6, as well ascoupling rolls 13. As regards the operation of the coupling device 8,the foregoing description is herewith incorporated by reference.

Still further shown in the figures is that the pattern plate exchangecarriage 4 can brought or moved below the downward rotated pattern platecarrier 6. To this end, reference may be made in particular to FIGS.4-8. The pattern plate exchange carriage 4 is designed for movement byhand, or an electric motor, or via a hydraulic or pneumatic cylinder,which is left open in the illustrations selected in the figures.

Provided below the pattern plate carrier 6 is a lifting mechanism 14with a receiving device 15, which can be moved, respectively forremoving or lowering, and for raising or installing pattern plate 1, 2,toward same or toward the pattern plate carrier 6. As further shown inthe figures, the receiving device 15 mounts two disengagement cylinders16 for opening and closing a pattern plate clamping connection 17 whichis provided on pattern plate carrier 6. This clamping connection 17 isbest seen in FIG. 1A.

Finally, as can be noted from the sequence of the method steps shown inFIGS. 4-8, the pattern plate exchange carriage 4 can be positioned withthe particular support 5 or pattern plate 2 below the downward rotatedpattern plate carrier 6 and above the lifting mechanism 14 or receivingdevice 15.

As previously indicated, the sequence selected in FIGS. 1-9, shows theindividual steps of the method of changing pattern plates during theproduction of Croning shell molds with the use of a tool changing devicein accordance with the invention, as has been described above in moredetail. Essential is in any event the fact that a pattern plate 2 whichis prepared for an exchange, be preheated to the working temperature andmaintained thereat, so that a heating of the new pattern plate 2 in themachine is no longer necessary. With reference to FIGS. 1-9, theparticularly advantageous steps of the method in accordance with theinvention are briefly described in the following.

FIG. 1 illustrates pattern plate carrier 6 mounting pattern plate 1which is in use. The pattern plate carrier 6 is connected, via couplingdevice 8, to pouring vessel 7. Moreover, FIG. 1A shows in a separateview, a clamping connection 17, which secures the pattern plate 1 topattern plate carrier 6. The pattern on both pattern plates 1, 2 isindicated only by its contour 18.

As illustrated in FIG. 2, the pouring vessel 7 is already tilted upwardby means of pivoting device 10, so that the pattern plate carrier 6 isdisengaged. In FIG. 3, the pattern plate carrier 6 rotates, togetherwith pattern plate 1 still secured thereto, by 180°, so that the patternplate 1 is directed downward, as shown in the illustration selected forFIG. 4. As this point in time, as can be noted from the embodimentselected for FIG. 4, the pattern plate exchange carriage 4 has movedalready below the downward rotated pattern plate carrier 6, with theempty support 5 of pattern plate exchange carriage 4 being positionedexactly below the pattern plate carrier 6.

As best seen in FIG. 5, for the actual exchange of pattern plates, thereceiving device 15 of lifting mechanism 14 moves toward the downwardrotated pattern plate 1. In this process, the pattern plate 1 isdisengaged by means of disengagement cylinders 16 associated withreceiving device 15. Accordingly, the pattern plate 1 can now bereceived by receiving device 15 and be lowered onto the free support 5of pattern plate exchange carriage 4. To this end, reference may be madeto FIG. 6.

FIG. 7 shows a further step of the method, wherein the pattern plateexchange carriage 4 has again been moved, namely for positioning thepreheated substituting pattern plate 2 exactly below the now emptypattern plate carrier 6.

Subsequently, the preheated substituting pattern plate 2 is raised bymeans of receiving device 15 or lifting mechanism 14 toward the emptypattern plate carrier 6. The pattern plate 2 is secured, again bydisengagement cylinders 16, but in reversed manner to the aforesaidrelease of the pattern plate 1 that is replaced.

As shown in FIG. 8, the empty receiving device 15 is retracted, so thatthe support 5 having originally carried the substituting pattern plate 2remains empty. Subsequently, the pattern plate exchange carriage 4 ismoved out of the working or pivoting range of pattern plate carrier 6,so that same can be rotated to its upward directed position, and beengaged with pouring vessel 7 by lowering same. This state is shown inFIG. 9, wherein the pattern plate exchange carriage 4 having been movedsideways carries now the replaced pattern plate 1, which may, forexample, be cleaned or stored. A next tool change will occur inaccordance with the foregoing description.

Finally, it should be noted that the above-described embodiment of atool change device in accordance with the invention as well as themethod steps relating thereto serve only for a descriptive illustrationof the teaching of the invention, without limiting same to the foregoingembodiment.

We claim:
 1. An apparatus for changing pattern plates in the productionof shell casting molds comprisinga pattern plate carrier for releasablymounting a pattern plate, means mounting said pattern plate carrier forrotation about a horizontal axis and between an upright position and aninverted position, and pattern plate changing means for removing apattern plate from the pattern plate carrier and replacing the removedpattern plate with a pre-heated substituting pattern plate while thepattern plate carrier is rotated to said inverted position.
 2. Theapparatus as defined in claim 1 wherein the pattern plate changing meanscomprises a carriage having at least two supports, with the carriagebeing movable so that each of the supports may be selectively positionedbeneath the pattern plate carrier in the inverted position.
 3. Theapparatus as defined in claim 2 wherein each of said supports includes areceiving device for supporting a pattern plate, and a pre-heatingdevice for pre-heating a pattern plate supported on said receivingdevice.
 4. The apparatus as defined in claim 3 wherein each of saidreceiving devices is separable from its associated support, and furthercomprising a lifting mechanism positioned below the pattern platecarrier for lifting a receiving device from a support positioned belowsaid pattern plate carrier so that the receiving device can release andremove a pattern plate from the inverted pattern plate carrier orreplace a removed pattern plate with a pre-heated substituting patternplate.
 5. The apparatus as defined in claim 4 wherein said pattern platecarrier includes a releasable clamping connection for releasablymounting a pattern plate thereon, and wherein each of said receivingdevices includes means for releasing or closing the clamping connection.6. The apparatus as defined in claim 5 further comprising a pouringvessel mounted adjacent said pattern plate carrier and so as to berotatable about a second horizontal axis which is parallel to the axisof rotation of said pattern plate carrier, and a coupling devicereleasably interconnecting the pattern plate carrier and the pouringvessel so as to permit the pattern plate carrier to be rotatable betweensaid upright and inverted positions upon release of said couplingdevice.
 7. The apparatus as defined in claim 6 wherein said couplingdevice is releasable upon rotation of said pouring vessel about saidsecond axis.
 8. The apparatus as defined in claim 3 wherein saidpre-heating device of each of said supports is adapted to heat a patternplate supported thereon to a working temperature of between about 250degrees C. and about 330 degrees C.
 9. A method of changing patternplates during the production of shell casting molds and utilizing apattern plate carrier which is configured to releasably mount a patternplate, and comprising the steps ofrotating the pattern plate carrierwhich mounts a pattern plate from an upright position to an invertedposition, releasing and removing the pattern plate from the patternplate carrier while in said inverted position, and then releasablymounting on the pattern plate carrier a substituting pattern plate whichhas been pre-heated to a working temperature of between about 250degrees C. and about 330 degrees C.
 10. The method as defined in claim 9wherein the pattern plate carrier is mounted for rotation about ahorizontal axis and between the upright position and the invertedposition, and wherein the step of releasing and removing the patternplate from the pattern plate carrier comprisesmoving a first support toa position below the inverted pattern plate carrier, lifting a receivingdevice from the first support to the inverted pattern plate carrier andreleasing the pattern plate therefrom so that the pattern plate issupported on the receiving device, and lowering the receiving device andthe supported pattern plate to the first support.
 11. The method asdefined in claim 10 wherein the step of releasably mounting on thepattern plate carrier a substitute pattern plate comprises the stepsofmoving a second support to a position below the inverted pattern platecarrier, with the second support supporting the substituting patternplate which has been pre-heated to said working temperature, lifting thepre-heated substituting pattern plate from the second support, andsecuring the lifted substituting pattern plate to the inverted patternplate carrier.
 12. The method as defined in claim 11 comprising thefurther subsequent step of rotating the pattern plate carrier and thesecured substituting pattern plate from the inverted position to theupright position.
 13. The method as defined in claim 12 wherein apouring vessel is mounted adjacent said pattern plate carrier and so asto be rotatable about a second horizontal axis which is parallel to theaxis of rotation of said pattern plate carrier, and a coupling devicereleasably interconnects the pattern plate carrier and the pouringvessel so as to permit the pattern plate carrier to be rotatable betweensaid upright and inverted positions upon release of said couplingdevice, and wherein the step of rotating the pattern plate carriertogether with a pattern plate from the upright position to the invertedposition includes releasing said coupling device.
 14. The method asdefined in claim 12 wherein the step of rotating the pattern platecarrier and the secured substituting pattern plate from the invertedposition to the upright position includes recoupling said couplingdevice so as to interconnect the pattern plate carrier and the pouringvessel.